Introduction and methods

Macrovascular disease, including coronary artery disease (CAD) and cerebrovascular disease, is one of the leading causes of morbidity and mortality for patients with type 2 diabetes (T2DM). Several studies indicate that bariatric surgery may reduce macrovascular complications of T2DM when compared with standard care [1]. However, these studies often lack the ability to study contemporary bariatric surgery due to a small number of patients [2] and because BMI measurements are unavailable which makes it impossible to identify a cohort of nonsurgical matches [3].

This retrospective observational matched cohort study assessed risk of macrovascular disease in T2DM adults (n=5,301) aged 19-79 years with severe obesity (BMI ≥35) who underwent bariatric surgery between January 1, 2005 and December 31, 2011, and who were matched to control patients (n=14,934) based on site, age, sex, BMI, HbA1ac, insulin use, observed diabetes duration, and prior health care utilization.

Patients were classified as having T2DM if they met one of two criteria at the time of procedure: 1) T2DM with HbA1c ≥6.5% or fasting glucose level ≥126 mg/dL at the most recent measurement within two years prior to surgery, or 2) medication-treated T2DM with current prescription for any oral of injectable diabetes medication at the moment of bariatric surgery. The primary outcome was time to incident macrovascular disease (composite of CAD or cerebrovascular disease) and the secondary outcomes were CAD or cerebrovascular disease as considered separately, and all-cause mortality.

Patients with bariatric surgery had a significantly lower 5-year incidence of CAD (1.6% in the surgical group vs 2.8% in the nonsurgical group; HR: 0.64 [95%CI: 0.42-0.99]). At the 7 year timepoint, the incidence of CAD was not statistically significantly lower in the surgery group (HR: 0.56, 95%CI: 0.29-1.08).

The risk of cerebrovascular disease of the surgery vs. the non-surgical controls fluctuated in time and was no longer significantly lower at the 5- and 7- year time points (5-year: 0.7% vs 1.7% ; HR: 0.69 [95%CI: 0.38-1.25], 7-year: HR: 1.1% vs. 2.3%, HR: 0.58 [95%CI: 0.25-1.36]).

Conclusion

This retrospective cohort study showed lower risk of macrovascular outcomes in T2DM patients with severe obesity who underwent bariatric surgery, compared with matched controls who did not undergo surgery. These data indicate the importance of the role of health care professionals in engaging T2DM patients with severe obesity in a shared decision-making conversation about the potential role of bariatric surgery in the prevention of macrovascular events.

Editorial comment

In their editorial comment [4], Sheka et al. note that intensive medical control alone does not improve clinical macrovascular outcomes while bariatric surgery has beneficial effects on CV health in addition to glycemic improvements. The authors summarize results of the Diabetes Surgery Study, showing not only improved HbA1c and LDL-c levels, and reduced systolic blood pressure, but also induced weight loss in T2DM obese patients with bariatric surgery as single intervention, compared with lifestyle-medical management. The authors conclude that access to bariatric surgery is, however, in the United States, limited by stringent private insurance requirements, lack of Medicaid coverage in some states, and high out-of-pocket costs. ‘Fisher et al. provide additional evidence that bariatric surgery is associated with lower rates of macrovascular events. Given the benefits of bariatric surgery for patients with type 2 diabetes, including potentially greater long-term benefits than most pharmaceuticals, insurance coverage for weight loss operations should be expanded for appropriate patients’.